With recent advances in communication technologies, old communication systems and newly developed communication systems coexist in the same region or country. For example, in European countries, second generation GSM (global system for mobile communications) systems and third generation WCDMA (wideband code division multiple access) systems are used together. Mobile terminals used in a region where various communication systems coexist include a component usable in at least one communication system.
These mobile terminals are designed to receive various messaging services such as a short message service, multimedia message service and electronic mail service. To support various messaging services, existing communication network systems are equipped with separate servers corresponding to distinct messaging services. In other words, an existing communication network system has separate servers corresponding to distinct messaging services.
For more effective management of messaging servers, advanced communication network systems are starting to provide a converged IP messaging (CPM) service unifying various existing messaging services. A CPM service is a convergent service combining a short message service, multimedia message service and electronic mail service together. However, it is necessary to build a new communication network to provide this CPM service. That is, providing a new CPM service requires a new communication network.
Building new communication networks may require protocol changes and replacement of network facilities. However, it is very difficult to suddenly upgrade existing communication networks. Hence, it is inevitable that existing communication networks coexist with new communication networks. Accordingly, it is necessary to develop a technique enabling a CPM service in an environment where existing and new communication networks coexist.